This invention relates generally to sheet pile constructions. More particularly, this invention relates to a process for effecting sealed sheet pile constructions and a device for application of a sealant to assure an impermeable sealed sheet pile construction.
Metallic sheet pile assemblies must, in a great many cases, be impervious to water, other liquids or to products dissolved or suspended in such fluids as well as such gases as are for instance, generated within dumping grounds. There is a particular need for an economical process for rendering sheet pile assemblies impervious to liquids and gases and a device for applying sealants into the interlocks of sheet piles that assures proper spread and distribution of the sealant.
It is well known in the art that the edges of sheet piles have an overall shape which either shows a flat web or has a U-shaped or a Z-shaped section fabricated, in such a manner, that one sheet pile may be connected to another contiguous sheet pile. These shaped edges, called interlocks, are inserted by sliding or by threading one interlock into the other or mating interlock. Whatever the specific configurations and particular names of the known interlocks, after assembly of a particular set of two sheet piles, one to the other, there results a certain amount of play within the set of interlocks. This inner play on the one hand permits the sliding or threading of the individual interlocks into one another without seizing up. On the other hand, the resulting assembly is left with a large amount of flexibility and mobility.
It is relatively easy to render such interlocks tight and impervious when such sheet piles are assembled together at the plant in units of two or three sheet piles. However, it is not possible to treat such interlock joints once the interlock joints have penetrated into the soil or any other below ground situation by sliding one interlock within the other interlock of a pair of interlocks since the interlocks are no longer accessible. Now there are all kinds of construction sites that do not allow impervious sealing of the interlock joints of sheet piles in the field. Particularly difficult are waterside construction sites. Even more difficult challenges are the containment of dumping grounds and slag tips. It is obvious that a more effective and permanently tight seal is required.
One of the known methods to provide tight and impervious sheet pile assemblies has been disclosed in the German Patent DE-PS-27-22-978. In accordance with this prior art method, a product of a fluid or plastic consistency is applied under pressure onto the bottom surface of the interlock in such a way that this product sticks to the interlock bottom as a result of the action of the pressure. The still malleable bead thus deposited into the interlock is then spread and shaped with the aid of a kind of"scraper blade". This "scraper blade" confers to the bead the desired shape on the preselected wall part of the sheet pile before the product hardens by polymerization. This operation must be completed quickly so that the product remains elastic for the next operation. The interlock so treated is inserted or drawn into a non-treated interlock which has already been driven into the soil or ground.
There are several problems associated with this prior art method. In the first place the use of the recommended sealing compounds presupposes that the bottom of the interlock is perfectly clean. In addition, it requires that the interlock has been rendered free of mill scale by sandblasting and that the interlock was thereafter painted with a primary coating so that the product will stick where the product has been deposited so that the seal may be shaped as hereinabove described. These steps, are as a rule, carried out manually and successively. Even if, in accordance with this prior art patent, only every second interlock is treated for each sheet pile, or double or even triple sheet pile unit belonging to a sheet pile assembly, it is obvious that these sheet pile assemblies each have to be treated individually. The aforementioned treatment requires successive operations. This results in a slow, tedious and expensive process.
There are several additional drawbacks to the elastic tightness and impervious seal as provided in the prior art patent. Firstly, the shape of the elastic seal may not be very uniform if the deposited bead contains too much or too little sealant. Secondly, it is difficult to maintain a straight seal as a result of the smoothing operation. Thirdly, it appears that it is almost impossible to apply the sealant in the forward acute angle corner of the Larssen interlocks with the manual tool as taught in the prior art patent.
However, the biggest drawback of the aforementioned prior art elastomeric product seals is that the thus treated sheet piles cannot be driven into the soil or ground with assurance that the interlocks will remain impervious to liquids and gases when the sheet piles are driven by a vibratory pile driver. The vibratory pile driver causes less nuisance and problems and is therefore often preferred to ram hammers. Indeed, the seal fissures and becomes detached and damaged due to the high temperature and friction caused by the vibratory pile driver or like device. The detached part of the seal rolls up and accumulates at the top of the interlock of the already driven sheet pile. The excess material clogs up and eliminates the play between the two interlocks. This excess material causes scraping and crumbling over what is often a very important and critical distance. It is obvious that as a result of such damage, the seal, if indeed there is even some of the seal left, no longer retains the required imperviousness.
From the foregoing discussion, it can be seen that there is a need for a process for rendering tight sheet pile constructions that is simple, easy and inexpensive to use which results in a seal that is not subject to damage and achieves optimal tightness over the entire length and surface of the interlock in contrast to the prior art.